Method for placing a pile or anchoring pile into ground

ABSTRACT

Method for placing a concrete-structure load-bearing pile or anchoring pile into the ground, in which method by means of hits generating device ( 3 ) a pile hole forming equipment, like with an end piece ( 5 ) equipped tube ( 1, 17 ) is forced into the ground to an intended depth (S) to a place meant for the intended pile, after forcing concrete mass is lead into said tube ( 1, 17 ) and simultaneously the tube ( 1, 17 ) is drawn out of the hole by means of the hammering device ( 3 ) wherein concrete mass fill the space meant for the final pile and the end piece ( 5 ) remaining as a pile top. It is generated to the pile load bearing ability or anchoring pulling strength increasing shapes ( 8 ) in the pile front end or after desired distances by means of stopping or making slower the drawing up of the tube ( 1, 17 ) immediately in the beginning of the draw-up portion and allowing the concrete mass to form a widening portion ( 8 ) in the pile front portion either for increasing the pressure of the concrete mass or for producing vibration by means of hammering device ( 3 ) to the tube  1, 17 ) and concrete mass or by using both above mentioned together.

The invention relates to a method for placing a concrete-structure load-bearing pile or anchoring pile into the ground, in which method another device, like with an end piece equipped tube is forced by means of a hammering device into the ground to an intended depth and to a place meant for the intended pile, after forcing concrete mass is lead into said tube and simultaneously the tube is drawn out of the hole by means of the hammering device wherein concrete mass fill the space meant for the final pile and the end piece remaining as a pile top.

Earlier is known the method according to the preamble from patent publication EP 1134319 B1, in which publication in addition to the above a sealed end piece is presented said piece connected to the tube which is forced into the ground, said end piece prevents water entering into said tube in water content ground. The tube is forced into the ground by means of a vibrating device which impacts in the upper end of the tube. The concrete mass is cast into the tube which is simultaneously drawn up from the ground.

As a disadvantage for the above described method is that of its body high and heavy pile hammering device is needed, said device further has mass concentration in its upper end so, that only vertical tubes or very little tilted 5-10° tubes can be hammered into the ground. Tube is possible to be drawn up by means of this kind of device only if the hammering device is such a vibrator being able to change the hammering direction. Inclinedly locating anchoring piles and inclined supporting piles are not possible to manufacture by means of this kind of method. Further this kind of from the top hammering pile driver needs space in the vertical direction remarkable more than what is the height of the pile, which has importance when worked under hinder, like bridges. The from top hammered or vibrated piles also try to turn due to in the ground met hinders, disturbing pieces or inclined layers easily to inclined direction and the pile becomes as inclined pile. This pile has not the same load bearing ability than the vertical pile has and it also needs more reinforcing steels.

Further is known forcing of the ready concrete pile into the ground, wherein to its upper end is hammered generally by means of a drop hammer. As a disadvantage for this pile is that its load bearing ability cannot be added after hammering into the ground. When forced into the ground it bears load by means of the front piece and pile side friction. It must be hammered so deep, that desired load bearing is formed by means of these two frictions when it acts as a load bearing pile or desired pulling resistance is formed, if it has been intended to be an anchoring pile. The load bearing capacity can be estimated by means of the produced advance due to the drop hammer at each moment.

The needed pile driver is also in this case remarkable higher than the pile and heavy and the ready piles must be forced essentially in vertical direction into the ground. Disadvantage for this ready pile is that it may break during forcing, because great hammering hits are directing to it, said hits producing respectively great opposite vibrations back which vibrations may break the pile made of concrete. In some cases this pile needs reinforcing steels only when hammered into the ground, no more when being as a load bearing pile, wherein the steel reinforcements are useless additive charge.

Due to in the above described known methods existing weaknesses and defects a new method has been developed, by means of which forcing of a concrete pile into the proper depth is solved, further essential increase of the load bearing and pulling resistance to get them bigger than what the hammering resistance was been during hammering as well as manufacturing the pile in different angles even in horizontal direction especially in anchoring meaning. Characteristic for the method according to the invention is, that it is generated to the pile load bearing ability or anchoring pulling strength increasing shapes in the pile front end or after desired distances by means of stopping or making slower the drawing up of the tube immediately in the beginning of the draw-up portion and allowing the concrete mass to form a widening portion in the pile front portion either for increasing the pressure of the concrete mass or for producing vibration to the tube and concrete mass or by using both above mentioned together.

Advantageous for the method according to the invention is, that the pre-hole for the concrete pile can be made very quickly by means of the into the ground forged and re-usable tube, because the tube has little side friction, wherein the tube penetrates into the ground easier than for example ready concrete pile. The quality variations in the ground become very well observed during forcing, because the front piece in the tube is essentially the biggest producer for the forcing resistance. In the place of the big forcing resistance in the ground the walls of the pile hole also become most strengthened. This strengthening acts advantageously also as buckling support for the pile. The received quality knowledge of the ground is utilized when searching locations for the shapes which increase the load bearing ability for the pile. Thanks to the side grip taken by the pile driver the pile driving can be made by means of the hammering device connected to an excavator, by which also the tube can be drawn up from the ground. Thanks to the vibration generated by the hammering device the flow of the concrete mass can be adjusted when the tube is lifted up from the ground. Pile driving needs space over ground surface only 2-3 metres more than what is the length of the pile to be forced into the ground. The pile can be mounted in vertical direction by means of side grip vibration better than when hammered from the top, wherein the need of the concrete reinforcement steels decreases.

The weight sounding belonging nowadays to the researching methods, by which weight sounding the load bearing ability and the length of the pile are concluded, can be excluded by using this method according to the invention when the advance of the first into the ground forced tube is observed. In other case if the weight sounding is carried out, the needed length of the pile according to this invention can be concluded.

By means of the invention essentially greater load bearing ability can be obtained for the produced pile, what can be estimated based on the forcing resistance of the tube. When the smooth forcing tube in this invention changes to a shaped, widening portions comprising concrete pile, essential increase in the load bearing ability is achieved as well as increase in the pulling resistance for the produced pile. These increases will multiple the load bearing or pulling resistance even 3-5 times compared with the respective ones of the smooth forging tube. It follows also, that the needed pile lengths will shorten or the pile distances from each other can be lengthened. The widening portions according to the invention can be made at the pile length in correct points, when during forging of the tube the strength changes in the ground is observed. By the method according to the invention also into the ground mounted vertical load bearing pile can be made, which has adjusted minimum cross-section area, for example side lengths 200 mm, and which pile as such a pile does not need reinforcement steels.

In the following the invention is closer described with reference to the accompanying drawings, where

FIG. 1 shows forging of a tube into the ground in side view.

FIG. 2 shows a front piece of a tube.

FIG. 3 shows a tube forged into the ground to a final depth S.

FIG. 4 shows observation of the ground quality made during tube forging based on the advancing speed of the tube and based on certain hammering force.

FIG. 5 shows a draw-up of a tube and casting of a concrete pile.

FIG. 6 shows a ready concrete pile in the ground.

FIG. 7 shows forging of a tube into the ground in inclined angle.

FIG. 8 shows ready anchoring pile in the ground.

FIG. 9 shows section view of a lower portion of a pile as a version having tube inside.

FIG. 10 shows a cross-section of a tube and an inclined pile.

In FIG. 1 forging of a steel tube 1 into of its quality variable ground by means of an excavator 7 connected hammering device 3 is presented. There has been gripped to the tube 1 by means of the hammering device 3 with a side grip, wherein the upper end of the tube 1 is open. The tube 1 includes one connecting point 2 for additional one. On the ground in this case already in advance a mould/pile bowl 4, via opening in the bottom of which bowl the tube 1 is forged into the ground. In the lower end of the tube 1 locates a front piece 5, which has been coupled to the tube 1 so, that its fixing means allows at least the transferring of the tube 1 in the start point of the forcing. The ground comprises different kind of ground qualities, like surface layer of the ground A, a soft ground type B, harder ground type C and hard moraine ground type. By means of the hammering device 3 the hits can be directed downwards during tube forcing and also upwards during its pulling-up.

In FIG. 3 the tube 1 locates in the depth S, which has been considered to be sufficient wherein additional ones to the tube 1 are not needed. The front piece 5 of the tube has met hard moraine ground and the advance of the tube due to the hammering hits has essentially decreased. The reference depth has been then achieved, which has earlier been calibrated for example by weight sounding.

In FIG. 4 there is shown, how the observations have been stored of the advance of the tube 1 and a schematic presentation has been formed of them, in which the forcing depth S of the tube as meters is as horizontal axis the advancing speed V mm/s of the tube is as vertical axis in forcing when the forcing is made by hammering device 3 the hammering energy of which has been kept constant. It can be seen from the figure that the advancing speed is higher in softer ground B than in the harder ones A, C and D. The method comprises that the piling depth is solved based on the load bearing ability requested for the pile. The pre-knowledge of the load bearing ability of the pile is already got, when the magnitude of the resistance caused by the tube so called reference force is observed at the end moment of the forcing. The load bearing value of the tube 1 is inversely proportional in relation to the advancing speed V of the tube at the end moment of the forcing. In the example the forcing is stopped when the advancing speed of the tube 1 has decreased to the in advance defined speed value Vref. The earlier mentioned reference force corresponds to this. This reference speed/force can be experimentally determined for the tube 1 when certain hammering device 3 is used. A reference force obtained by weight sounding and the reference force from the end moment of forcing according to the invention can also be calibrated to correspond each other. This kind of decrease in the speed during forcing indicates that the ground is more compact and has better load bearing ability. The advancing can naturally fully stop, when the front piece 5 has met rock or big stone or the resistance is as great as the hammering force.

In FIG. 5 there is presented the pulling-up of the tube 1 by means of a hammering device 3. After a little pulling-up, about 0.5 m the concrete mass is tried to be led down to the front piece 5 so that the mass due to pressure, pressure shocks or vibration caused by the hammering device 3 spreads around the front piece 5 and makes a widening portion 8 around it. The pulling-up can be then made slower or stopped it. There inside the tube 1 a reinforcement, for example spiral-shaped concrete strengthening steel 11 has already in advance located or it is dropped inside the tube 1 before concrete casting. The front piece 5 is to the purpose so slightly fixed to the tube 1 that it loosens from the tube due to the concrete casting and remains in the bottom of the hole. Concrete mass is lead via adapter part 10 and tube 9 inside the tube 1. The widening portion 8 is tried to form to as the lowest part of the pile riot depending on the quality of the ground at this point. The conical front piece 5 compacts the pile hole and compacted hole side hinders the hole to collapse and to mix with the concrete and also get better support against the inclined load directed to the pile.

The tube 1 is presented in FIG. 6 fully pulled out and widening portions 8 have been made also at two other points, where in advance softer ground type has been observed, the concrete pile is ready and in the upper end of the pile concrete has also been cast in the mould/pile bowl 4 and the mould 4 removed so that pile hat 13 remains. During casting reinforcing steels have been placed in the pile hat 13.

When the pile is ready and includes widening portions 8 as well as of concrete made indefinite side portion its load bearing ability has increased essentially compared with the ability which was obtained for the into the ground forced tube 1. The final load bearing ability for this kind of pile can be experimentally determined and based on the sufficient amounts of samples it is possible to determine, how the load bearing ability for the final pile can be obtained from the load bearing ability of the tube 1 when said tube acted as a pre-pile.

The manufacturing of the anchoring pile by the same method is presented in FIGS. 7 and 8. The tube 1 can be forced by means of a combination of the excavator 7 and a hammering device 3 into different angles and an anchoring rope 15 has already been coupled to the front piece 5 the end of which rope is extending out of the pile after concrete casting. Also in this case is possible based on the pulling resistance of the tube 1 at the end moment of the forcing to determine the pulling resistance for the final pile when pulled it from the rope 15.

Inside the tube 1 in FIG. 9 locates another tube 16 which remains as a pile casing covering at least part of the pile length, preferably in area having very soft ground type. The tube 16 is allowed in the beginning to rise a little, in order to the widening portion 8 will be formed in the lower end.

FIG. 10 shows an advantageous cross-section shape of tube 17 for inclined pile. Oval tube 17 is advantageous, because then at the pulling side of the load, a little sidewards of the pile centre line the reinforcing steels 18 can be more surely placed and said steels are needed also less than in the previous described round tube 1 case. In the pressure side of the concrete pile the reinforcement steel are not needed and it may due to its inelasticity loosen from the concrete. Concrete is in pressurized situation more flexible than steel. 

1. Method for placing a concrete-structure load-bearing pile or anchoring pile into the ground, in which method by means of hits generating device (3) a pile hole forming equipment, like with an end piece (5) equipped tube (1);(17) is forced into the ground to an intended depth (S) to a place meant for the intended pile, after forcing concrete mass is lead into said tube (1);(17) and simultaneously the tube (1);(17) is drawn out of the hole by means of the hammering device (3) wherein concrete mass fill the space meant for the final pile and the end piece (5) remaining as a pile top, and that it is generated to the pile load bearing ability or anchoring pulling strength increasing shapes (8) in the pile front end or after desired distances by means of stopping or making slower the drawing up of the tube (1);(17) immediately in the beginning of the draw-up portion and allowing the concrete mass to form a widening portion (8) in the pile front portion either for increasing the pressure of the concrete mass or for producing vibration by means of hammering device (3) to the tube (1);(7) and concrete mass or by using both above mentioned together, characterized in that as a hammering device (3) by means of side grip to a tube (1);(17) gripping equipment is used, by which equipment the tube (1);(17) is forced into the ground to different angles, if needed, and the hammering direction of which equipment is changed to opposite direction during the pulling up action of the tube (1);(17) and said widening portion (8) is formed in the pile at the point in the ground, which has been observed to be softer of its type than other observed point at the pile length downwards (S).
 2. Method according to claim 1 characterized in that in connection with tube (1);(17) forcing the quality data of the ground is observed and stored as a function of the depth value (S), for example by observing the advancing speed (V) of the tube (1);(17) when the hammering device (3) works with constant power.
 3. Method according to claim 1 characterized in that the forcing depth (S) for the pile is determined when the tube (1);(17) advance in forcing decreases to a certain advancing value for example to reference speed (Vref) mm/s when hammered with a certain hammering energy of the device (3).
 4. Method according to claim 1 characterized in that in connection with the forcing of the tube (1) inside it and covering at least part of the pile length (S) another tube (16) is mounted inside which concrete is cast and which tube (16) is left in the hole with the end piece (5) as a shell for the concrete pile when the tube (1) is pulled out.
 5. Method according to claim 1 characterized in that before the casting of the concrete mass into the tube (1);(17) the needed reinforcements, like concrete steels (11);(15),(18) or pulling ropes (15) are mounted inside the tube (1);(17).
 6. Method according to claim 1 characterized in that a column which extends the minimum cross-section area and has no concrete reinforcements is manufactured by the method.
 7. Method according to claim 1 characterized in that the casting of the concrete mass is stopped at the mould (4) locating at the point of the pile on the ground surface and by means of said mould a pile hat has been formed as an upper surface for the pile.
 8. Method according to claim 1 characterized in that the upper end of the tube (1) is open and, if needed, an additional tube (1) is coupled to it as well as for concrete casting an adapter part (10) for tube (9) via which tube concrete mass is pumped into the tube (1).
 9. Method according to claim 1 characterized in that the pile hole, especially inclined pile hole is forced by means of a tube, the cross-section area of which tube deviates from ring shape, like by means of an oval tube (17). 